1. Technical Field
The present invention relates to an optical disk device and an optical disk processing system having the optical disk device, and in particular to detection of a transparent disk.
2. Related Art
When a CD or a DVD is mass-produced, the manufacturing cost is reduced using a large-scale device having a disk changer. On the other hand, an optical disk processing system is proposed in which a recording unit which writes information on the optical disk, a printing unit which prints on a label surface of the optical disk, and a disk changer are integrated, in order to handle cases of custom-made optical disks which do not require mass production such as, for example, school learning materials, commemorative items, presents, etc. In this optical disk processing system, a sequence of processes are automatically executed in which an optical disk which is not yet processed is transported from a stocker to a recording unit and loaded, data is recorded by the recording unit, the recorded optical disk is ejected, the recorded optical disk is transported to the printing unit and a print is applied on the label surface, and the printed optical disk is again transported back to the stacker. JP 3797318 B discloses an optical disk processing system in which a recording unit, a printing unit, and a disk changer are integrated.
There may be cases where a protection transparent disk having approximately the same shape as the optical disk, and which protects the optical disk, may be equipped in the stocker, and the optical disk processing system may take out the protection transparent disk and transport to the recording unit. When the protection transparent disk is transported, the optical disk device which is the recording unit stores the transported protection transparent disk and irradiates laser light from an optical pickup, to attempt to focus. However, because the disk is a transparent disk, there is no return light, and the controller of the optical disk device would erroneously judge that there is no disk. JP11-345453A discloses a configuration where a photosensor is provided sandwiching the disk, and scattered light from the optical disk is detected, to detect the state of no disk, or three states indicating disk existing (normal disk, disk present, semitransparent disk).
However, in the above-described related art, because scattered light created at a reflection surface of the optical disk is used, it is not possible to judge the protection transparent disk through which the laser light completely transmits, and which causes no scattered light.
There is also known a method for judging the existence/non-existence of a disk by driving a spindle motor and measuring a load (inertia) applied on the spindle motor based on the startup time and number of rotations. With this method, it is possible to detect that there is a disk, even for the protection transparent disk. However, when the device attempts to focus, because there is no return light, retrying of the focus would be repeatedly executed multiple times, and there is a problem that a certain amount of time is required until an error is finally judged.